K630 - V640 - K660
1215-3608 rev. 1
FUNCTIONAL OVERVIEW
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WCDMA Transceiver Block Diagram
Transmitter
The TX IQ modulator has differential voltage I and Q inputs. It converts input signals to
RF output frequency and is designed to achieve LO and image suppression.
The transmit output stage provides at least +5 dBm at maximum power control at the
single-ended 50
Ω
output. Gain is set through the 3-wire bus.
Two 10-bit DACs are used to control the DC/DC converter and the PA gain. These DACs
are controlled through the 3-wire bus.
Receiver
The front-end receiver converts the aerial RF signal from WCDMA band I down to a Zero
Intermediate Frequency (ZIF). The first stage consists of one single-ended low noise
amplifier (LNA) with a 16 dB gain step. This LNA is followed through an external filter by
an IQ down-mixer which consists of a mixer in parallel driven by quadrature out-of-phase
LO signals. The In phase (I) and Quadrature phase (Q) ZIF signal are then low pass
filtered to provide protection from high frequency offset interferer fed into the channel
filter.
The front-end zero IF I and Q outputs are applied to the integrated low-pass channel filter
with a provision for 4 x 8 dB gain steps in front of the filter. The filter is a self-calibrated 6
pole, 2 zero filter with a cut-off frequency around 2.15 MHz and a second order group
delay compensation (2 poles, 2 zeroes). Once filtered, the zero IF I and Q signals are
further amplified with provision of 31 x 1 dB steps and DC offset compensation. The zero
IF output buffer provides close rail-to-rail output signals.
Bluetooth and FM Radio
The STLC2592 circuit N1400 combines Bluetooth and FM tuner functionality into one.
Bluetooth
The Bluetooth implementation is compliant with Bluetooth specification 2.1 + EDR.
The Bluetooth
TM
transceiver has frequency channels with 1 MHz separation from 2402 to 2480
MHz. The same band is used for both transmission and reception. This gives 79 frequency
channels.
Receiver
The first stage of the receiver is an external antenna filter, which suppresses unwanted
frequencies. The receiver is of a “near-zero” IF receiver architecture. The local oscillator is
generated by a frequency synthesizer, which allows the receiver to be set at frequencies in
intervals of 1 MHz. The synthesizer is controlled from the logic part.
The received signal is sampled in the logic for later signal processing.
Transmitter
The synthesizer generates the TX frequency which modulated by the BT baseband block. It is
then amplified. The BT system is a class 1 device with maximum of +4 dBm output power
(minimum setting is about -50 dBm).
FM Radio
FM Receiver
The receiver uses a digital low-IF architecture. The receive (RX) section integrates a low noise
amplifier (LNA) supporting the worldwide FM broadcast band (76 to 108 MHz). An automatic
gain control (AGC) circuit controls the gain of the LNA to optimize sensitivity and rejection of
strong interferers. An image-reject mixer down converts the RF signal to low-IF. The
quadrature mixer output is amplified, filtered and digitized with high resolution analog-to-digital
converters (ADCs). This advanced architecture allows the use of digital signal processing (DSP)
to perform channel selection, FM demodulation and stereo audio processing.
Tuning
The receiver uses frequency synthesizer technology including a completely integrated VCO. The
frequency synthesizer generates the quadrature local oscillator signal used to downconvert the
RF input to a low intermediate frequency. The VCO frequency is locked to the reference clock
and adjusted with an automatic frequency control (AFC) servo loop during reception. The tuning
frequency is defined as:
Freq (MHz) = Spacing (kHz) × C Bottom of Band (MHz)
External Connectors
External units are connected to the transceiver by means of a 12-pin connector on the bottom
of the phone. The pin numbering is starting from the right when looking at the system
connector with the front up.
Technical Description
SEMC Troubleshooting Manual
73
(96)
